The invention relates to a method and a service providing means for supporting services, to which a subscriber of a first telecommunication network has subscribed, in a second telecommunication network, when a mobile station roams from said first to said second telecommunication network. The invention also relates to a telecommunication network comprising such a service providing means.
In particular, the invention relates to a situation, where a subscriber has subscribed to specific services in the first telecommunication network and part of the services or a complete service is differently implemented in the second telecommunication network, when the mobile station roams to the second telecommunication network or when a call is to be routed to the second network.
FIG. 5a shows a telecommunication system TELE, which comprises at least two different telecommunication networks HPLMN, VPLMN. Both networks HPLMN, VPLMN are, for example, mobile radio communication networks, for example according to a GSM specification, NMT (Nordic Mobile Telephony) specification, a TACS specification or a DECT specification. The first network HPLMN could, for example, be constituted by the D1 or D2 network in Germany and the second visiting network VPLMN could be the TELECOM network in Italy. In this case, the two networks HPLMN, VPLMN are geographically separated. However, it is also possible that a mobile station MS is provided with the option of using two different networks in one country. Hereinafter, the first network will be called the home network HPLMN and the second network will be called the visiting network VPLMN, independently as to whether the two networks geographically overlap or not.
FIG. 5a shows that each of the mobile radio communication networks comprises the usual functionalities of a home data base, formed by a home location register HLR, HLRxe2x80x2, switching means, formed by a mobile switching center/visitor location register MSC/VLR, MSC/VLRxe2x80x2, and gateway mobile switching centers GMSC, GMSCxe2x80x2, which basically link the two networks. It should be noted that the units GMSCxe2x80x2, HLRxe2x80x2, SNxe2x80x2 (a service node which will be explained below) are not used by a mobile station MS roaming from the home network HPLMN, but will be used of course by a mobile station MS which belongs to VPLMN (i.e. which regards VPLMN as home network). Furthermore, it is possible that the GMSCxe2x80x2 is part of an IPLMN (interrogating PLMN) network in case of optimal routing which is indicated with the x-x-x line in FIG. 5a. Normal routing (used in today""s networks) and optimal routing (contemplated for future use) will be explained below with reference to FIGS. 5b, 5c. 
Different procedures are invoked when the mobile station MS (belonging to the home network HPLMN) roams from cell to cell in the home network HPLMN and when the mobile station MS roams to the visiting network VPLMN. When in the first case, as shown in the home network HPLMN, the mobile station MS just roams from cell to cell, e.g. from one MSC/VLR to another MSC/VLR in the same home network (indicated with the dotted arrow in HPLMN), a location updating procedure is performed with respect to the subscriber data stored in the home location register HLR, such that each MSC/VLR is always provided with the relevant subscriber data of the subscriber whose card has been inserted into the respective mobile station MS. In this case, a roaming detection means for detecting when said mobile station MS roams from one cell to another cell can be viewed as being constituted by parts of the base station system and parts of the mobile station. For example, during an on-going call a handover of the mobile station is carried out when the roaming detection means detects that the signal strength has decreased below an acceptable level such that another MSC/VLR should take over the communication. On the other hand, if the mobile station does not participate in call and is merely switched on, then at least the location updating procedure is carried out.
In the second case the mobile station MS roams to the visiting network VPLMN (indicated with the dashed arrows in FIG. 5a) in a state where it is switched on or in a case where it is only switched on after having entered the visiting network. In this case, the mobile station MS must register at the respective MSC/VLRxe2x80x2 of the visiting network VPLMN which will request a copy of the relevant subscriber data to be sent from the home location register HLR of the home networks HPLMN, where the mobile station MS (more precisely the subscriber whose card is inserted into the mobile station) is registered.
A similar situation occurs when a call is to be routed to a mobile station MS which has roamed to a visiting network VPLMN. FIG. 5b shows the case of a normal routing and FIG. 5c shows the case of an optimal routing.
If e.g. in FIG. 5b a call is to be routed from MS1 to MS2 (a terminating call for MS2) then the GMSC will request HLR to provide routing information (step ST1). The HLR requests this information from MSCxe2x80x2 (step ST2) which provides the information to HLR (step ST3). Then the information is forwarded to GMSC (step ST4) which canxe2x80x94on the basis of the received routing informationxe2x80x94route the call to MS2 (step ST5). It should be noted that the call terminating scenario in FIG. 5b is in principle also valid if a call is originated from a terminal of a fixed network connected to the home HPLMN. Also in this case the call is first routed to the GMSC of the network HPLMN which then requests the routing information from MSCxe2x80x2.
Optimal routing as in FIG. 5c alway relates to terminating calls (IPLMN does not exist for originating calls). When the further network IPLMN (IPLMN: interrogating network for terminating calls) is provided, in case of optimal routing, the routing principle is exactly the same as in the case of normal routing, the difference being that the gateway MSC GMSCxe2x80x2 resides in a different PLMN (i.e. IPLMN) That is, also in this case, terminating calls are always routed to the GMSCxe2x80x2 which requests HLR for the routing information of MS2. HLR always knows where the MS2 is roaming and requests as in the case of FIG. 5b the respective MSCxe2x80x2 in the visting network to provide e.g the roaming number (steps ST1-ST5; note that the x-x-x line in FIG. 5c corresponds to the x-x-x line in the general diagram in FIG. 5a). The difference between FIG. 5b, and FIG. 5c is that in FIG. 5c the terminating call is directly routed from the GMSCxe2x80x2 to the MSCxe2x80x2 in the visiting network (VPLMN) where the mobile station MS2 is registered.
If both networks only provide the normal GSM services to the mobile station MS and the subscriber has only subscribed to these normal services in the home network HPLMN, then no problem with the roaming to the visiting network VPLMN and the terminating of calls to the mobile station MS in VPLMN occurs in all cases in FIG. 5a, 5b, 5c, since the format of the subscriber data and/or service data which are stored in the home location register HLR in HPLMN and the format which the VPLMN can handle is the same. For example, a call forwarding number specified by the subscriber in the home network HPLMN will immediately be understood and can be processed also in the visiting network VPLMN, so that such types of information can immediately be copied and used in the MSC/VLRxe2x80x2 of the visiting network VPLMN.
However, problems exist if some services, to which the subscriber has subscribed in the first network HPLMN, or an additional service are/is differently implemented in the visiting network VPLMN. For example, when the service is not supported in the visiting network VPLMN, of course any format of data relating to such services will not be understood can not be processed in the visiting network VPLMN. Indeed, such a situation can arise, since nowadays a subscriber in the home networks HPLMN has the option to subscribe to several new services provided in the home network HPLMN in addition to the services already provided by the network operator, e.g., the normal GSM services according to the GSM standards. On the other hand, a service (normally available with a subscription in the home network HPLMN) or an additional service to which the subscriber has subscribed to in the home network HPLMN may be as such available in the visiting network VPLMN, only that it is differently implemented, e.g. due to a different network standard. If in such a case the subscription data is forwarded from the MSCxe2x80x2 in the visiting network VPLMN upon a request from the home network HPLMN, then it cannot be understood since it will e.g. have a different format not known in the home network HPLMN.
Additional services can be viewed as being provided by an additional service provision means ASPM, which may be constituted by a service node SN, SNxe2x80x2 in the respective network. For example, the mobile subscriber may have a subscription to a CAMEL or IN (Intelligent Network) like service and in this case, the home location register HLR will contain some subscriber data and/or service data relating to such additional services. For example, the CAMEL services may be provided by a so-called CAMEL service environment CSE shown in FIG. 5a. According to GSM specifications, the CSE may be provided by the GSM/SSF (GSM Service Switching Function) and the GSM/SCF (GSM Service Control Function) nodes. More specifically and as shown in FIGS. 5b, 5c for home PLMN services the ASPM unit always resides in the home network HPLMN, i.e. the additional service provision is always done from the home network HPLMN, even when the mobile station roams to the visiting network. The SSF (which communicates with the ASPM; see step ST6 in FIGS. 5a, 5b) can reside in either the IPLMN or the VPLMN. In case of a realisation in terms of a Service Node SN or traditional IN (IN: Internet Network), it can also reside in the HPLMN as schematically indicated in FIG. 5a. In the special case of additional services being provided by a CAMEL environment as in FIGS. 5b, 5c, the SSF is integrated with the GMSC and/or the MSCxe2x80x2 and/or the GMSCxe2x80x2.
Thus, there are various possibilities of where the service providing means ASMP can be located in the network HPLMN and VPLMN. Some special GSM services (functions) may be provided by functionalities always provided in a GSM type network according to the GSM specification. Nonetheless, the mobile subscriber will need a separate subscription to these special services.
However, independent as to where the ASPM and/or the SSF and/or the SCF is located, there are always the above described problems that for various reasons a service which was fully available to the mobile station in its home network will not be available when it roams to the visiting network. If the mobile subscriber has, for example, a subscription to CAMEL or IN like services (as indicated in the subscriber data of HLR in FIG. 5a) in the home network HPLMN and is roaming in the visiting network VPLMN which cannot support this functionality, this mobile subscriber cannot use certain GSM mobile telephony services due to the interaction or mismatch problems. Also, when a mobile subscriber has subscribed to a CAMEL phase 2 service, which e.g. specifies a xe2x80x9cforwarded-to-numberxe2x80x9d in a non-GSM (E.164) format, and is roaming in a network not supporting this CAMEL phase 2 service, he cannot use normal GSM call forwarding functionalities, although this is according to the GSM standards. The same problem occurs also when a user roams to a different network than a GSM network (e.g. from a GSM type network to a DECT/NMT/TACS type network as indicated in FIG. 5a). Thus, the problem of unavailability of service occurs in any situation where a mobile subscriber roams to a visiting network where a service is not supported, where a service is differently implemented, or where a service is implemented with different features.
For the case when a service which the mobile subscriber has available in the home network is differently implemented in the visiting network VPLMN, FIG. 6 shows in connection with FIG. 5a what happens when a mobile station MS (e.g., the mobile subscriber) roams to the visiting networks VPLMN in step S1. In any case, the mobile station MS must register at the MSC/VLRxe2x80x2 (i.e. a roaming detection means formed by parts of the MSC/VLRxe2x80x2 and the mobile station MS detects that there is a new mobile station MS in the visiting network VPLMN for which the visiting HLRxe2x80x2 has no subscriber data). Essentially, the MSC/VLRxe2x80x2 requests a copy of the subscriber data from the home HLR in step S2 and (possibly simultaneously) the visited MSC/VLRxe2x80x2 indicates to the home HLR the services that are supported in the VPLMN. If the visited network VPLMN supports a special service, this means that the functionalities in all units of the visited network VPLMN can process subscriber data and/or service data relating to such a service. Although it may be noted that the service itself will still be provided to the mobile station from the home network HPLMN, even if it roams in the visited network VPLMN, the functionalities in the visited networks VPLMN must be adapted to process such service data which a visited network VPLMN only does if in principle it also supports these services through its own independent service node.
For the case of providing CAMEL type services, according to GSM standards, the home HLR should check in step S4, if the visited MSC/VLRxe2x80x2 supports, e.g., CAMEL in case the mobile subscriber has a subscription CAMEL in the home network HPLMN. I.e., in step S4 the home HLR determines on the basis of the information indicated in step S3 which of the services to which the mobile subscriber has subscription in HPLMN are supported in the visited network VPLMN. If all services are provided (xe2x80x9cYxe2x80x9d in step S4), then the HLR sends all subscriber data and/or service data contained in the HLR for the respective mobile subscriber to the visited MSC/VLRxe2x80x2 in step S5. When some services are not provided (xe2x80x9cNxe2x80x9d in step S4), then the HLR sends to the visited MSC/VLRxe2x80x2 all subscriber data and/or service data except the data relating to the non-supported services in step S6. For example, if CAMEL is not supported, HLR will not send CAMEL data to the visited MSC/VLRxe2x80x2. The same principle is applied for IN like services in GSM, NMT and TACS, i.e. whenever it is determined in the first network HPLMN that not all services are supported in the second network VPLMN, only part of the subscriber data and/or service data is copied into the visitor MSC/VLRxe2x80x2.
This causes a practical disadvantage, since, for example, a call forwarding number specified in a CAMEL service which the mobile subscriber indeed can use in the HPLMN, cannot be used when the mobile subscriber is in the visited network VPLMN, although in principle the visited network VPLMN has such call forwarding functionalities as well.
However, due to the format mismatch data cannot be used in the visited network.
As explained above, in a telecommunication system TELE there may arise situations where a mobile subscriber who has a subscription to a plurality of services in his own home networks HPLMN can only use part of the functions of the services in the visited network, since the services are either not supported there or the functions or functionalities of the service may in principle be available in the visited network VPLMN, are however differently implemented.
Therefore, the object of the invention is to provide a method, a service providing means and a telecommunication network which allow a mobile subscriber to use functions (features) or functionalities of one or more services to which he has a subscription in the home network also in the visting network, even if in the visiting network the functions (features) or functionalities are differently implemented, e.g. according to a different network standard, thus avoiding problems when attempting to use the functions (features) or functionalities of the service(s) available in the visiting network.
Solution of the Problem
This problem is solved by a method (claim 1) for supporting features of services, to which a subscriber of a first telecommunication network has subscribed, in a second telecommunication network, when a mobile station has roamed from said first to said second telecommunication network, comprising the following steps: determining in said first network whether features of one or more services to which said subscriber has subscribed to in said first network are supported or are supported differently in said second network, sending a conversion request message from a home database of said first network, in which the subscriber data and/or service data for each subscribed service is stored for each subscriber, to a service providing means, which provides the features of the subscribed services in said first network, said request message indicating subscriber data and/or service data relating to features of the subscribed services which have been determined as being supported differently in said second network, converting in said service providing means the format of said subscriber data and/or service data relating to features of services supported differently in said second network to a subscriber data and/or service data format of at least one service which is supported in said second network, and sending a response message containing said subscriber data and/or service data having said converted format back to said home data base.
Furthermore, this problem is solved by a service providing means (claim 7) for providing features of services, to which a subscriber of a first telecommunication network has subscribed, in said first network, including a conversion means for converting, in response to a conversion request message, which is issued from a home database of said first network, in which the subscriber data and/or service data of each subscribed service is stored for each subscriber, when a mobile station roams from said first to a second telecommunication network, and which indicates subscriber data and/or service data relating to features of subscribed services differently supported in said second network, the format of the subscriber data and/or service data relating to features of said differently supported services to a subscriber data and/or service data format of at least one service which is supported in said second network, and a response means for sending a response message containing said subscriber data and/or service data having said converted format back to said home data base.
Furthermore, this problem is also solved by a telecommunication network (claim 13) providing to a mobile station services to which a subscriber of said mobile station has subscribed to in said network, comprising: a home data base in which the subscriber data and/or service data of each subscribed service is stored for each subscriber of said network, a service providing means for providing said services in said network, a roaming detection means for detecting when said mobile station roams into another network in which at least one of said subscribed services is differently supported, said home database sending to said service providing means a conversion request message indicating subscriber data and/or service data relating to features of subscribed services which are differently supported in said another network when said roaming detection means detects said roaming of said mobile station, said service provision means comprising: a conversion means for converting in response to said request message the format of said indicated subscriber data and/or service data relating to features of the services supported differently in said another network to a subscriber data and/or service data format of at least one service which is supported in said another network, and a response means for sending a response message containing said subscriber data and/or service data having said converted format back to said home data base.
Essentially, according to the invention, a format conversion of the subscriber data and/or service data relating to functions (features) or functionalities of services which are supported differently in the visiting network is performed and the subscriber data and/or service data for functions (features) or functionalities of services which are supported together with the subscriber data and/or service data having the converted format are transferred to the visiting network. Since the conversion is always done into a format which can be understood and processed in the visited network VPLMN, the mobile subscriber can always use at least part of his originally subscribed services (functions) of the home network HPLMN also in the visited network VPLMN, even if the function (feature) is differently (i.e. with a different format) implemented in the visiting network.
Preferred Aspects of the Invention
If the visited network VPLMN supports the requested function (feature) or functionality of one or more services in several different implementations (formats), then the conversion means of the service providing means in the home networks HPLMN has the option to convert the format of the function in the home network into a selected one of the several formats used by services in the visited network VPLMN. That is, the conversion means can convert the format of the function data (subscriber data and service data) of functions of the services in the home network into a specific format of a service which supports these functions in the visiting network. Alternatively, the conversion means can convert the format of the functions (subscriber data and service data) also to respectively different formats of services in the visiting network which are best adapted to the function used in the home network HPLMN.
Preferably, a request message directed to the conversion means of the service providing means can contain an additional indication that further conversions should be performed whenever it is detected that a specific item of the subscriber data and/or service data has changed over time, which then causes a forwarding of the converted changed subscriber data and/or service data to the visiting network (the visited mobile switching center). For example, whenever a call forwarding number changes according to the time of day, a further conversion and sending of a message to the visited mobile switching center can be performed.
Further advantageous embodiments and improvements of the invention can be taken from the dependent claims. Hereinafter, the invention will be described with reference to its advantageous embodiments with reference to the attached drawings. In particular, it should be noted that the embodiments of the invention comprise combinations of features which have been separately described and listed in the claims and in the description. Hereinafter, a description of the invention follows with reference to what is currently considered to be the best mode of the invention.